Art of burning gas



Dec. 10, 1940.

W. P. BIDDLE, JR

ART OF BURNING GAS Filed June 19, 1956 Patented Dec. 10, 1940 ART OF BURNING GAS William P. Biddle, Jr., Knoxville, Tenn., assignor to Knox Stove Works, Knoxville, Tenn., a, corporation of Tennessee Application June 19, mesj'sn'al No. 86,163

9 Claims. (Cl. 158-99) The present invention relates to improvements in the art of burning gas and is particularly advantageous with gas burners of the so-called atmospheric type.

A primary feature of the present invention is the production of such anatmospheric mixture under a pressure slightly above atmospheric pressure in a plenum chamber, with the subsequent passage of this combustible gaseous mixture 10 along a port or passageway having a restricted spacing of its walls so that the gaseous mixture flows in a thin sheet, for a distance which preferably is at least twenty times the spacing of said walls, and then is delivered in a sheet for providing a long stable flame.

Another feature of the present invention is the provision of a gas burner having inner and outer conduits which are spaced apart to pro vide an annular space or port for the flow of 20 aseous mixture in a peripheral direction therearound, the pipes being provided with orifices at diametricaly opposite points so that the gaseous mixture in the inner pipe is caused to move through the orifice thereof and thence along the 25 outer wall of this inner pipe to the discharge .orifice of the outer pipe. 1

A further feature of the present invention is the provision of a gas burner in which structures are provided for constituting a plenum 30 chamber and walls providing a passageway for the fiow of a long thin sheet of gas between these walls and for a distance in the direction of flow which is preferably between twenty and fifty times the thickness of the flowing sheet.

35 With these and other features as objects in view, an illustrative form of practicing the invention is shown on the accompanying drawing, in which:

Fig. 1 is a longitudinal elevation of a gas 40 burner acording to this invention.

Figs. 2 and 2a together show a longitudinal sectional view through such a gas burner.

Fig. 3 is a transverse sectional view substantially on line 3-3 of Fig. 2. j

45 Fig. 4 is a sectional view corresponding to Fig. 3, but showing a modified form of construction.

In this specification-and claims, the expression port is used to designate a passage through which the combustible mixture flows on its way 50 to the point of combustion. The depthof this port is essentially the distance traversed by the molecules of the gas in their movement from a plenum chamber, as a source of supply for the port, to the point of escapefor individual.combustionrthe width of the portis-the thickness of the sheet of flowing mixture at the corresponding part of the passageway and the length of the port is the dimension of its surfaces at right angles to the direction of flow. Thus the port area is the product of the length and width 5 of the port at a particular section thereof, and the total port area is the sum of the areas of the individual ports where more than one is present.

In the drawing, the gas burner illustrated is of the type which may be utilized in the oven of a gas range, or for like employments, and delivers a long sheet of flame which is maintained substantially uniform so long as the gas pressure delivered to the jet tube is uniform.

The gas supply tube In delivers gas to the usual regulating valve I l and thence to the jet tube [2 which extends into a Venturi tube I3. The inlet end of the Venturi tube is provided with a supporting plate l4 for centering the jet. g tube I2, and with the rotatable air damper it which may be moved in the usual way for regulating the quantity of air admitted into the Venturi at a given gas delivery from the jet tube I2.

The discharge end of the Venturi is illustrated as having a radially projecting flange 20 which is threaded at its outer periphery and has a shoulder 21 at its interior. A coupling or union nut 22 engages thethreads of the flange 20 and has an inwardly projecting flange 23 of the usual type.

The burner head proper comprises an inner tube or conduit 25 and an outer tube or conduit 26. These are illustrated as of cylindrical form so that their adjacent wall surfaces substantially conform to one another, but it will be understood that other forms may be employed. These conduits may be of sheet or cast iron, brass, or

other materials suitable to the purpose.

The inner tube 25 provides a plenum chamber in which the combustible mixture is under pressure and from which it escapes on its way to the point of combustion. For this latter purpose, the tube 25 has a slot 21 therein which usually is directed downwardly when the burner is in position. The outer tube 26 has a slot 28 which usually is directed upwardly when the burner is in position. Thus the. slots 21 and 28 are diametricaly opposite one another at each point of length of the burner head. In the illustrated form, they extend along the length of the tubes, from end to end thereof, and parallel to the aids. Thus, these tubes may be easily and simply manufactured.

The cross-sectional area of the plenum chamber is related to the total port area. Where the port is provided by uniformly spaced conduits, the port area is uniform throughout the depth of the port or ports; and where the spacing of the parts or width of the port varies, the port area at the mouth or discharge point for combustion is taken herein as the standard, as it is customary to have this area small in order that the velocity of the issuing gases may be large, to prevent back firing. The cross-sectional area of the plenum chamber should be at least 1% times the total port area of the port or ports served thereby; an increase in the size-raatio of the plenum chamber is of advantage, but it is usually unnecessary to have the plenum chamber area more than three times the port area, as the increased effect beyond this ratio is relatively small.

The inner tube has its outer surface of a diameter less than the diameter of the inner surface of the outer tube by a distance dependent upon the type of gas being employed, upon the sizes of the tubes themselves, and upon the gas pressures available at the supply pipe In. It has been found, however, that with gases of the type employed in many cities, this spacing may be of the order of one-sixteenth of an inch and then operates satisfactorily under the varying conditions prevailing in different communities. The diameters of the tubes 25 and 2B are so selected that the circumferential dimension of the inner tube is preferably forty to one hundred times the spacing of the tubes, that is, the inner tube may have an external diameter from three-fourths of an inch to two inches when used under normal conditions with city gas, and with a total port area of around 0.35 square inch.

The inner tube 25 is illustrated as longer than the outer tube and extends into engagement with the shoulder ii of the Venturi flange 20, Preferably, the internal diameter of the discharge end of the Venturi flange is the same as the internal diameter of the inner tube 25, so that there may be no obstruction to flow of the gaseous mixture from the Venturi tube [3 into 'the plenum chamber provided by the inner tube 25. The outer tube 28 is illustrated as provided with a collar or ring 29 which may be formed integral therewith'or brazed or welded thereon. This collar 255 is gripped by the flange 23 of the union nut 22 so that the outer tube 26 is pressed against the'end surface of the flange 20 duringassembly, while at the same time the close conformation of the aperture of the union nut 22 to the external diameter of the outer tube assures the proper spacing of the two tubes at this end.

At the free ends of the tubes 25 and 26, they are provided with closing means in this illustrated form. These closing means comprise the cups 30 and 3 I, which in the form shown in Fig. 1 are provided with inwardly directed flanges 30a, 3Ia closely fitting inside of the respective tubes. These cups are preferably brazed or welded to their respective tubes. Each of these cups, further, is provided with a boss 33 which is eccentric to the axis of the tubes, and thus they cooperate in locating the slots 2-! and 28in proper diametrical position with respect to one anothen, The cups 30'and 3| are presented close against one another, or in contact with one another, when the union nut 22 is drawn down, so that there is no short-circuiting of gas along the ends of the tubes 25 and 26 to increase the relative amount of gas delivered to the outer slot 28 adjacent the free end of the tubes.

In the modified form shown in Fig. 3, the structure is substantially the same as before, except that the inner tube is provided with an external rib 3t which provides a spreader for the gas arriving at the slot 28 through the two peripheral passageways provided by the two half peripheries in the annular space between the tubes 25 and 26, and deflects these streams of gas outwardly away from the axis of the tubes 25 and 26. This arrangement is advantageous in some cases, as a clogging of one-half of the annular space does not lead to an objectionable deformation of the flame.

The structures thus provided are easily manufactured and assembled, and can be easily separated for cleaning in the event of any fouling in the passageways which constitute the deep ports. ihe structure is compact and takes up no more space than a conve'ntional "burner of the shallow pofttype.

The burner thus provided operates in a highly satisfactory manner, and is "practically free of "flashback. The great uniformity of pressure prevailing throughout the length of the discharge orifice or orifices, =by'the employment of the deep ports, which in'the illustrated form extend for'a full h'alf periphery of the tubes, gives practically a true streamline fio'w with little or no turbulence.

VJi'th the ordinary burner having a plurality of small ports, nonuniformities of pressure arise, from various reasons such as a slight turbulence. When a flame once starts down a port, the rate of combustion increases the back pressure in such "a port, so that theflame tends to continue to travel and to cause a flashback or combustion in the Venturi or plenum chambers. may take place even when the average velocity of the airgas mixture exceeds the 'rateof flame propagation. With'the present arrangement, however, a very simple construction, capable of easy cleani'n'g; provides a long deep 'por t having a p'a'ssageway which in the direction of flow of the gaseous mixture is preferably at least twenty ti'm'e's -the thickness of the flowing s'tre'aim of gas, Further,

- the provision or this passageway by metal walls which are being cooled by air flowing upwardly around the outer wall-and by thegaseous m ixture entering rrom the 'ven turi, 'Of itself p'IOdUcEs a coming or check ing effect-Which will extinguisha flame propagating within the annular space, It may be 's'tated that thebu-r'ner is ableto withstand a-sudden turn-down from maximum gas'input to one-tenth o'f such input"without flashback.

This stability of burner performance permits the utilization of ahigher percentage of primary air, thus giving a high efficiency in the 'appli'ance because smaller combustion chambers are permissible, the flame temperature is increased, and v the requirement of secondary air above the burner is reduced to a minimum.

It is obvious that the invention may be employed in many other ways without departing from the scopeof the appended claims.

-I*claim:

-1. A gas burnercomprisi'ng astructure having 'an internal cavity providing a plenum chamber and including a wall surrounding 'said plenum chamber save and except for a long slot located substantially at the bottom-ofsaid plenum'chamber, said structure also including a secon'dwall spaced from said flrst wall and providing there- ;with narrow passageways extending from said slot and providing-deeppor-tsofa length substantially equal to the length of said long slot and extending upward pastsaid plenum chamber at each side' thereof, said second wall being interrupted-at the top of the structure to provide a second long slot and providing an exit to atmosphere for combustible mixture moving from said plenum chamber through said ports, the crosssectional area of each said slot being greater than-the cross-sectional area of both of said ports, each said passageway providing a said deep port through which the gaseous mixture passes from said plenum chamber to the point of combustion and having a depth or peripheral distance along said firstwall from said first slot to said second slot which is sufficiently greater than the vertical dimension of the plenum chamber and sufiiciently narrow to diminish the region of the flash-back curve and insure passing of the gas in a sheet through said ports.

2. A gas burner comprising a first hollow element providing a plenum chamber, a second hollow element surrounding and spaced closely adjacent the first element, the adjacent walls of the elements being curved, means for supplying a combustible mixture into said plenum chamber, the space between said elements being in uninterrupted communication with the plenum chamber at the bottom of said chamber and along the whole length of said space so that said space provides opposite curved paths for the upward flow of the combustible mixture, said space being relatively narrow and deep to function as a port to diminish the region of the flash-back curve and insure passage of the gas in a sheet through said space, the second element having an opening extending the whole length of the second element for communication with the atmosphere at the top thereof, said opening having an area at least equal to the cross-sectional areas of fiow in said two paths, so that the portions of the mixture flowing in the opposite paths encounter one another adjacent the outer surface of the first element and are by this means diverted upwardly and discharged through said opening for combustion immediately above said second element.

3. A gas burner comprising an inner wall forming a plenum chamber and having an external curved surface, means for delivering a combustible gas into said chamber, an outer wall spaced uniformly about the inner wall to form a curved gas delivery port extending substantially the full length of the burner, said inner wall having a slot therein extending the full length of the burner for communicating between the plenum chamber and the port, said outer wall having a slot therein extending the full length of the burner for communicating between the port and atmosphere and disposed remotely with respect to the first-mentioned slot to extend the depth of the port, said port being relatively narrow and deep to diminish the region of the flash-back curve, and said slots each being considerably wider than said port to assure smooth and continuous flow of the gas into the port and from the port in a sheet without abrupt change of directional fiow or back pressure.

4. A gas burner comprising a structure having an internal cavity providing a plenum chamber and including a wall surrounding said plenum chamber save and except for a long slot located substantially at the bottom of said plenum chamber, said structure also including a second wall spaced from said first wall and providing therewith narrow passageways extending from said slot and providing deep ports of a length substantially "equal to the lengthof said long slot and extending upward past said plenum chamber at each side thereof, said second wall being interrupted to provide a second long slot substantially diametrically opposite the first long slot and providing an exit to atmosphere for combustible mixture moving from said plenum chamber through said ports, the cross-sectional area of each said slot being greater than the cross-sectional area of both of said ports, each said passageway providing a said deep port through which the gaseous mixture passes from said plenum chamber to the point of combustion and having a depth or peripheral distance along said first wall from said first slot to said second slot which is at least twenty times its width whereby to diminish the region of the flash back curve and insure passing of the gas in a sheet through said ports.

5. A gas burner comprising a structure having an internal cavity providing a plenum chamber and including a first wall surrounding said plenum chamber save and except for a long slot located substantially at the bottom of said plenum chamber, said structure also including a second wall spaced from said first wall and providing therewith a narrow passageway extending from said slot and providing a deep port of a length substantially equal to the length of saidlong slot and extending upward and past said plenum chamber, said second wall being interrupted at the top of the structure to provide a second long slot substantially diametrically opposite the first long slot and providing an exit to atmosphere for combustible mixture moving from said plenum chamber through said port, the cross-sectional area of each said slot being greater than the cross-sectional area of said port, the peripheral distance along said first wall between said slots being at least twenty times greater than the distance between said walls.

6. A gas burner comprising an inner cylindrical shell forming a plenum chamber, means for delivering a combustible gas into said chamber, an outer shell spaced uniformly about the inner shell, to form a cylindrical combustible gas delivery port extending substantially the full length of the burner, said inner shell having a slot extending substantially the full length thereof for delivering combustible gas into said port, said outer shell having a slot extending substantially the full length thereof and disposed diametrically opposite the first-mentioned slot for delivering the combustible gas from the port to atmosphere, said port being at least twenty times as deep as it is wide, and said slots each being at least four times as wide as said port.

7. A gas burner comprising an inner wall forming a plenum chamber and having an external curved surface, means for delivering a combustible gas into said chamber, an outer wall spaced uniformly about the inner wall to form a curved gas delivery port having a width no greater than one twentieth of its length and extending substantially the full length of the burner, said inner wall having a slot therein extending the full length of the burner for communicating between the plenum chamber and the port and being of a Width not less than four times the width of said port, said outer wall having a slot therein greater in width than the first-mentioned slot and extending the full length of the burner for communicating between the port and atmosphere and disposed remotely with respect to the first-mentioned slot to extend the depth of the port.

8. A gas burner comprising an inner cylindrical shell forming a plenum chamber, means for delivering a combustible gas into said chamber, an outer shell spaced uniformly about the inner shell to form a cylindrical combustible gas delivery port extending substantially the full length of the burner, said inner shell having a slot extending substantially the full length thereof for delivering combustible gas into said port, said outer shell having a slot extending substantially the full lengththereof and disposed diametrically opposite the first-mentionedslot for delivering the combustible gas from the port to atmosphere, said port being at least twenty times as deep as itis wide and divided by said slots into two oppositely directed half-cylindrical port paths for the combustible gas encountering one another .di-

rectl'y in the outer shell slot and being by this means diverted upwardly through said outer shell slot for combustion immediately above the outer shell, said inner shell slot being, of a width not less than four times the width of said port, and said outer shell slot being wider than the inner shell slot.

9. A gas burner comprising an outer conduit having a slot extending along its length, an inner conduit having an external rib projecting into the slotof the outer conduit, said inner conduit communicating with the space between said conduits at points along its length which are substantially diametrically opposite to said rib, and means for supporting said conduits at a substantially uniform spacing distance.

WILLIAM P. BIDDLE, JR. 

